The present disclosure relates to humidity determining devices and environmental testers including the same.
For example, an environmental tester including a thermostat-humidistat container (chamber) has been used for stability tests of pharmaceuticals, or the like in order to test the performance of a product under predetermined temperature and predetermined humidity. In the environmental tester, a temperature sensor and a humidity sensor are provided in a test chamber of a thermostat-humidistat container surrounded by adiabatic walls, and an air conditioner including a refrigerator, a humidifier, and a heater is controlled based on values measured by these sensors. This allows circulation of air between the container and the air conditioner so that the temperature and the humidity in the container are kept to target temperature and target humidity, respectively (see, for example, Japanese Unexamined Patent Publication No. H07-140061).
In this case, macromolecule capacitive sensors are widely used as the humidity sensors. Such a macromolecule capacitive humidity sensor includes moisture-sensitive macromolecules provided on an electrode, and determines the humidity in the test chamber by measuring the dielectric constant of the moisture-sensitive macromolecules which changes according to the amount of moisture adsorbed onto the moisture-sensitive macromolecules.